One example of a cylinder lock provided for the trunk of an automobile is designed as follows. The lock is provided with a cover to open and close the front surface of the key rotor. Engaging parts are formed respectively on the cover and the lock body to maintain the cover open. The cover is urged by a spring so that it is normally closed.
The conventional cylinder lock with the cover is provided with the engaging parts to maintain the cover open during the key operation as was described above. However, the cylinder lock is disadvantageous in that the cover is not automatically returned to its original position; that is, in order to return the cover to the original position it is necessary to manually disengage the engaging parts from each other, and the operator often forgets to close the cover. In order to eliminate this disadvantage, the instant inventor has proposed a cylinder lock with a cover that is designed to remain open while a key that has been inserted into the key rotor is turned for unlocking. The cover is automatically closed upon removal of the key from the key rotor. This is described in Japanese Unexamined Utility Model Application No. 122354/84.
Recently, a trunk opener means has been employed in combination with a cylinder lock so that the trunk can be released without using the key. This is normally done by operating a lever provided near the operator's seat. While this is convenient it has the disadvantage that if the car doors are not locked, the trunk can be opened without using the key. Therefore, there is an increased risk that the things in the trunk may be stolen. Furthermore in the case where the automobile is loaned to another person, or the engine key is given to another person, for instance at a parking area, the trunk can be readily opened.
In order to overcome the above-described difficulties, a cancelling mechanism has been proposed that is designed so that if a key inserted into the key rotor of the trunk is turned through a predetermined angle in a direction opposite to the direction of unlocking, then it becomes impossible to open the trunk even if the lever is operated at the operator's seat. The cancelling mechanism is applied to an ordinary trunk cylinder lock that has no cover. However, since the present invention relates to a cylinder lock with a cover and is not based on the technical concept that the key is turned in the direction opposite to the direction of unlocking, it is impossible to combine the cylinder lock hereof with the cancelling mechanism previously known.